<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <script>
            window.number = 2;
            var obj = {
                number: 3,
                db1: function () {
                    console.log(this);
                    this.number *= 4;
                    return function () {
                        console.log(this);
                        this.number *= 5;
                    };
                },
            };
            var db1 = obj.db1;
            db1();
            obj.db1();
            console.log(obj.number);
            console.log(window.number);
        </script>
    </body>
</html>
